This invention relates to air intake pipes for mounting to the air filter on an internal combustion engine, and particularly to such pipes as are designed to suppress engine intake noises.
German Utility Model No. 1,900,418 discloses air intake pipes for use with the air filter of an internal combustion engine wherein there are provided multiple air-flow channels to cause acoustic wave interference between air intake noises, which arise during engine operation. Similar air intake silencing apparatus is described in an article in MTZ Magazine, No. 1940, page 49. In that article, there is also described a noise silencing intake pipe which is provided with holes, open to the surrounding air and arranged to act as a high pass filter for engine intake noises.
The prior art arrangements are particularly adapted to suppress low frequency engine noises or noises of a dominant frequency by providing interference or filtering.
It is an object of the present invention to provide a new and improved air intake pipe which provides the suppression of engine noises over a wide frequency range.
It is a further object of the present invention to provide such an apparatus which provides noise suppression by frictional acoustic damping as well as by acoustic wave interference.